Open AccessHolocene development of the Vaisjeäggi palsa mire, Finnish Lapland
Author(s) -
OKSANEN PIRITA O.
Publication year - 2006
Publication title -
boreas
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.95
H-Index - 74
eISSN - 1502-3885
pISSN - 0300-9483
DOI - 10.1111/j.1502-3885.2006.tb01114.x
Subject(s) - permafrost , mire , aggradation , peat , holocene , geology , macrofossil , radiocarbon dating , ridge , physical geography , geomorphology , oceanography , paleontology , archaeology , geography , structural basin , fluvial
A palsa mire in Finnish Lapland is studied by means of plant macrofossil analysis, physico‐chemical analysis and AMS radiocarbon dating of peat deposits in order to reconstruct its development. Emphasis was on permafrost dynamics during the Holocene. Mire initiation recorded at four studied sites took place between 8240 and 5210 yr BP, first through terrestrialization of a pond and, beginning from 6780 yr BP, through paludification of birch‐dominated uplands. Slow lateral expansion of the mire suggests relatively dry conditions in the region. Rich wet fens prevailed until the late Holocene, when changes connected with permafrost development occurred. First permafrost aggradation is recorded in a high palsa site at c . 2460 yr BP. The pathway of permafrost formation possibly points to a climate cooler than today. Permafrost aggradation in a ridge palsa site is dated to c . 645 yr BP, indicating an early Little Ice Age date. The long‐time average carbon accumulation rate in the four peat profiles is 16 gC/m 2 yr. In the older, high palsa, carbon accumulation during the palsa stage has been low (9 gC/m 2 yr), while in the younger, ridge palsa site it has been very high (73 gC/m 2 yr)